Process of making halolefines



Patented Dec. 11, 1923.

UNITED STATES PATET OFFICE.

HARRY ESSEX AND ALGEB L. WARD, OF WILMINGTON, DELAWARE, 'ASSIGNORS TO E. I. DU PONT DE NEMOURS & COMPANY, OF WILMINGTON, DELAWARE, A COR- PORATION OF DELAWARE.

PROCESS OF MAKING. HALOLEFINES.

{Ho Drawing.

To all whom it may concern:

Be it known that we, HARRY Essex and Anonn L. WARD, citizens of the United States, and residents of Wilmington, in the county of New Castle and State of Delaware, have invented a certain new and useful Process of Making Halolefines, of which the following is a specification.

This invention relates to a catalytic proclo ess of making a halolefine, and particularly an allyl halide, b splittin oif hydrogen halide from an a more than two carbon atoms such as a propylene halide. In general the new process com rises bringin a dihalopropane, such as ibromor die l'or-propane, in contact with a catalyst, for example calcium chloride, at a high-temperature to cause the splitting ofi therefromof hydrogen bromide or hydro n chloride.- The chemical reaction invo ved may be representedby the equation: CH,Cl-CHOl-CH,HC1= $5 CH,Cl-CH:CH,. It has heretofore been proposed to make allyl chloride from dichlorpro ane by allowing it to drop on a heated a kali metal or other metal or on a suitable heated alkaline 0 compound, as for example, metallic I magnesium, calcium or aluminum, or potassium hydroxide, sodium hydroxide, calcium hydroxide, or magnesium hydroxide.

In the course of our experimental work 95 we have found,'however, that the desired decomposition ma be more advantageously effected by passing the vapors of propylene chloride over a hot metal chloride such as calcium or barium chloride. The reaction 0 in this case is catalytic, the calcium or barium chloride remaining unchanged in the reaction tube. The hydrogen chloride may be removed from the reaction products sinpl by washing with water. I c5 e temperature of the metal chloride used as a catalyst should ordinarily be maintained between 200 and 400 0., and preferably from 300 to 350 C.

The new process may be illustrated by the followin example Propy ene chloride (that is, 1.2-dichlorpropane) is vaporized a tube containing anhydrous calcium ch lene ha ide containing consequently a little big and passed through Application filed October 14, 1919. Serial No. 830,651.

ride, the temperature of the tube being maintained at about 350 C.

The vapors issuing from the tube, and containing some unchanged propylene chloride, are subjected to fractional condensation by passing them through a condenser kept at about C. to separate said ropylene chloride. The liquid propy ene chloridethus separated is again vaporized and the va ors assed over the catalyst as before. T whichpropylene chloride has been remove are then condensed and treated as may be necessary to remove hydrogen chloride and other impurities that may be present.

The data and results of the best runs with each of the several different rea ents whichhave heretofore been pro ose and with catalysts which we have iscovered to be useful, are tabulated below Tam Pro Allyl Yield Contact material. ch10 d6 chloride 0!.

' consumed. formed. theoret.

Caustic soda 250 94.2 g. 8.5 g. 13.3 Calcium h droxide 325 145.7 g. 25.1 g. 25.5 Barium ch orlde 350 52.4 g. 8.5 g. 24.0 Calcium chloride. 350 71. 0 g. 31. 7 g. 65.0

The tem eratures iven in the table were taken in t e space between the tube containing the catalyst and the electrical heating element surroundin said tube and are er than the actual reaction temperatures.

Of the important advantages of our process there may be mentioned (1) that a much higher yield is obtained heretofore, (2) that the reaction is catalytic, and (3) that at the same temperature the rate of decomposition of. propylene chloride is several times as great with calcium chloride as with calcium hydroxide, the latter being the most feasible, from the commercial standpoint, of the reagents heretofore suggested.

We claim 1. The process of makin all 1 chloride which comprises bringing ich or-propane into contact with calcium chloride maintained at a temperature of from about 300 to 350 C.

2. The process of making allyl chloride which comprises passing vapors of propylobtained than has been e al yl chloride vapors from v ene chloride over calcium chloride maintained at a temperature between 200 and 400 C.

3. The process of making allyl chloride which comprises passing vapors of propylene chloride over calcium chloride maintained at a temperature of from about 300 to 350 C.

4. The process of making-a halolefine having a ha ogen-attached carbon'atom adjacent a pair of doubly bound carbon atoms, which comprises passing vapors of an alkylene halide containing more than two carbon atoms over calcium chloride maintained at a temperature of from about 300 to 400 C.

5. The process of making a chlorolefine having a chlorine-attached carbon atom adjacent a pair of doubly bound carbon atoms, which comprises passing vapors of an alkylone chloride containing more than two car- 7 bon atoms over calcium chloride maintained at a temperature of from about 300 to 400" C.

In testimony whereof we aflix our slg- 

